In the coming year we are investigating new methods of producing leukemia-specific heteroantisera in rabbits. In order to reduce antibody formation against normal lymphocyte antigens that are present on leukemia cells the rabbit and the immunizing cell will be treated with antiserum raised to normal lymphocytes. Using these methods we have produced specific ALL and AML antisera. The AML antiserum that we produced reacted with leukemia cells from 10/46 AML patients and 2/23 ALL patients. We are currently trying to produce AML antisera that has broader reactivity against AML cells. Attempts are also being made to produce high-titered specific ALL serum that may be useful in immunotherapy. We have produced an antiserum against the T ALL cell line HSB2 that reacts with 30-70% of peripheral blood T lymphocytes but is negative against B lymphocytes. Further studies will be carried out to determine the functions of the positive and negative subsets; for example MLC, PHA, and Con A responsiveness of each subset. We are also using specific B-cell and T-cell heteroantisera to detect B- and T-cell antigens on leukemia cells.